Cox PeeWee .020 Problems

bnitram Tue Jan 08, 2013 3:07 pm

Hi all,
I have a problem with a Cox PeeWee .020. Apparently the piston is higher than the outlet is deep. As you can see in the picture below.

What could be wrong?
Thanks for answer

bnitram

fredvon4 Tue Jan 08, 2013 3:31 pm

This is normal on many Cox engines. Referred to as SPI the idea is that the now exposed air inlet to the bottom of the crank case will fill with a bit of additional cool air and speed up the air fuel charge up through each transfer port. Not all Piston Cylinder combinations include SPI.

Some cylinders are cut with lower exhaust port to cause SPI and in other cases the piston skirt is reduced to cause SPI.....

Except with the muffler engines, SPI usually (not always) yields more power and higher RPM

bnitram Tue Jan 08, 2013 3:37 pm

Thanks for your answer.
I thought I had bought a broken engine but now i know.

Ok
Thanks!

**RknRusty** Tue Jan 08, 2013 4:37 pm

We have a couple of good threads on Sub Piston Induction, SPI. It is a high performance feature. Like Fred says, it doesn't agree with mufflers or exhaust restriction throttles.

bnitram Wed Jan 09, 2013 5:40 am

Ok. Thank for Info! Smile

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